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Hi I hope this is in the correct section.
i won’t ask how to repair the codes because google is full of those answers but i will ask if anyone knows if any of the following codes I'm getting can be ignored due to being caused by no emissions equipment or sensors that are not necessary in a basic LS 5.3/4L60E swap to a 71 Chevy pick up truck.
these are the following codes I’m receiving.
P0122 Throttle Position Sensor 1 Circuit Low Voltage (cheap eBay 92mm throttle body has bad tps alignment due to holes being off by about half an inch. had to modify tps to be able to rotate it enough to get it at correct voltage.)
P0351 Ignition Coil 1 Control Circuit (faulty new coil. Swapped coil packs with a spare set of used square coils and code went away.)
P0452 Fuel Tank Pressure Sensor Circuit Low Voltage (removed DTC from ecm not needed for vented aftermarket fuel tank)
P0706 Park/Neutral Position Switch Circuit
P0740 unknown
P1810 Transmission Fluid Pressure Switch Circuit
P1860 unknown
P0748 Line Pressure Control Solenoid Valve System Performance
(The final 5 codes on the list were all caused by poor continuity on the pink 12v wire that runs to the transmission on pin E.)
Last edited by Mr_Goodwrench; Jul 26, 2024 at 12:57 AM.
The fuel tank pressure is used to drive the EVAP purge system, so that one may not matter if you have a vented fuel tank. The rest of those indicate serious issues that must be diagnosed and fixed.
@gametech thank you for the help. I am indeed running a vented fuel tank. Hopefully someone can chime in and let me know how to shut that code off in the actual tune file.
I was able to resolve two of the codes today so I updated the post and included the fix that worked for me. Hoping it may help someone down the road. Also I’m thinking that all the codes related to the trans may be due to a 2008 4L60E being installed using a 05 LS ecm although I have read that backwards compatibility of newer 4L60E in older vehicles works but not older 4L60E in newer vehicles. Any info would greatly help if anyone knows anything.
In a DBW setup, if the pedals/tac module/throttle body/pcm are not all from a matching vehicle you may run into issues. This could be the cause of your TB code, but without more details on the swap, who knows?
Once you rule out bad electrical connections, if you still have the transmission codes I would recommend posting in the auto trans section. Frank and a few others there are quite knowledgeable.
Thanks @gametech I am taking tomorrow off to try to resolve these issues. I’ll be checking all electrical connections and if I don’t manage to resolve them I’ll be taking your advice and posting those last trans codes to the Transmission section. Again thank you for your help.
P0122 Throttle Position Sensor 1 Circuit Low Voltage
this was being caused by the poor alignment of the TPS due to the holes being drilled off by about half an inch on the cheap DBC 92mm eBay throttle body. Had to remove a lot of plastic and remove the little plastic locking tab on the TPS to be able to rotate it enough to get it to the correct reading.
Stayed up to 3am working on it and got rid of all my transmission codes. Turned out to be the 12v pin E on the harness having poor continuity. Replaced wire and tested the ground to make sure it was properly grounded. Success no more codes.
in case anyone has this issue pin E On the harness can be tested to make sure it has between 11v or 12v use the ground off the transmission harness to mimic the actual power that the transmission is receiving.
also when installing the connector make sure the side with the arrow is facing outward.
Just got out of work and back to it. Funny thought today… I recalled that I purchased and installed a brand new coil because the original coil #1 had a crack where the boot goes on so I’m thinking that the coil was an Amazon dud fresh out the box. I’m now in the process of installing an extra set of square coils that I have to see if anything changes. Will report back soon.
SUCCESS!!!!!
The “new” Amazon coil was indeed garbage fresh out the box. Installed the extra set of square coil packs and the code is now gone.
all that’s left is to do is turn off the code for the Fuel tank pressure sensor and reflash the ECU. Time for a well deserved ice cold beer 🍺
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codes that can be ignored after LS swap? (Solved) 
